Abiotic stress may be broadly defined as a group of nonliving factors, which can result in harmful effects to plants. Examples of abiotic stressors include excessive soil salinity (as well as other adverse soil conditions), drought, high winds, heavy metals, herbicides, and extremes of temperature. Such abiotic stressors may promote the generation of reactive oxygen species in photosynthetic cells, and cell death from abiotic stress may therefore be in part a result of oxidative damage.
As an example, agricultural practices and poor irrigation management in warm and dry regions often result in saline and gypsiferous soils with a low productivity. Indeed, secondary salinization resulting from poor irrigation management affects approximately 20% of irrigated land worldwide. Thus, abiotic stressors such as salt stress represents a serious limitation to soil productivity. Improving crop yields in soils subjected to salinity constraints and other abiotic stressors is a constant goal and need in the art.
A variety of methods have been considered to reduce harmful effects of abiotic stress, including genetic means such as addition of transgenes for antioxidants. Resulting improvements have been limited, however, due to the complexity of the plant antioxidant system, and to the numerous other elements of cell physiology contributing to (or detracting from) stress tolerance. There accordingly remains a need in the art for methods and compositions for improving resistance of plants to abiotic stressors such as high soil salinity. The present invention provides methods for reducing or preventing harmful effects of abiotic stress in plants, comprising application thereto of compositions comprising a yeast cell wall. Application of the compositions of the present invention surprisingly reduces or prevents the harmful effects of abiotic stressors such as high soil salinity in plants.